JLR: New cardiovascular-disease risk marker?

When red blood cells break down, so does hemoglobin. A byproduct of this breakdown, bilirubin, has been hypothesized to act as an antioxidant; some in vitro studies have suggested that low-density lipoprotein can be protected from breakdown by oxidation by bilirubin. This, along with the idea that bilirubin has anti-inflammatory properties, may explain why low concentrations of serum bilirubin are associated with a higher risk for cardiovascular disease.

Pernette R.W. de Sauvage Nolting and colleagues at the Academic Medical Center of Amsterdam, the Netherlands, investigate in the article “Serum bilirubin levels in familial hypercholesterolemia: a new risk marker for cardiovascular disease?” whether a statin can change blood bilirubin levels in people with familial hypercholesterolemia, a genetic disorder characterized by high levels of cholesterol, especially LDL. They also investigated whether bilirubin level was a reliable risk marker for cardiovascular disease.

Male patients between 18 and 80 years old who had one copy of the hypercholesterolemia gene were given a daily oral dose of statin for two years and followed for the entirety of this cross-sectional study.

The statin was shown to reduce total cholesterol, LDL and triglyceride levels while elevating high-density lipoprotein; but, more importantly, median bilirubin levels increased from baseline after treatment.

This increase was more obvious in patients who had been diagnosed with cardiovascular disease than those without cardiovascular disease.

While the study had limitations (particularly patients’ concurrent aspirin use and their lifetime smoking habits), the publication appears to be the first to consider bilirubin level as a potential risk marker in an FH population and proposes that long-term use of a statin can protect that population from cardiovascular disease.

Mary L. Chang (mchang@asbmb.org) is managing editor of the Journal of Lipid Research and coordinating journal manager of Molecular and Cellular Proteomics.